While harvesting bosonite on a barren world that they need to proto-warp back to Voyager the crew encounters aggressive, genetically-modified tribbles — and the Klingon scientist who created them.

The Prodigy crew and Chakotay reunite with Voyager, bringing the timelost Protostar with them. But the past catches up to them when Ilthuran delivers a dire warning — Asencia is coming.